Would it be a complicated job to fit a electric start to my DT 125r? Not very good with electrics but I know a thing or two

Yes. Very.

I know the rain is wet the wind blows and it hurts when you hit your thumb with a hammer so I know a thing or three.

Buy a later bottom.end with electric start. But really why? A two stroke can almost be started by hand?!

I agree...not worth the bother IMO, it's not unusual for owners of elec start models to fit the kickers from the earlier bikes

I find generally the leccy leg soaks power and you get a weak spark, I have had a couple of leccy start strokers , from cold they would kickstart first kick on the kicker , but crank all day on the leccy leg and not fire , my Z650 only has electric start, and is a right pain when been standing for a few days, better now with hot coils and a AGM battery, but if you bump it it fires into life immediately

I only want it as my DT takes ages to start when cold, I don't know why? What are the main things that would stop a 2 stroke from starting in the first 5 kicks?

lack of compression, need new spark plug/cap/lead, carburettor incorrectly set, choke not working

I'm going to check spark plug again, see if it sparks, I recently changed the plug. Also my Dt does not idle? I have to keep the revs up or it will cut out? Do you know anything about that?